How Facebook satisfied a need for speed

O'Reilly Radar: "Remember how Facebook used to lumber and strain? And have you noticed how it doesn't feel slow anymore? That's because the engineering team pulled off an impressive feat: an in-depth optimization and rewrite project made the site twice as fast.
Robert Johnson, Facebook's director of engineering and a speaker at the upcoming Velocity and OSCON conferences, discusses that project and its accompanying lessons learned below. Johnson's insights have broad application -- you don't need hundreds of millions of users to reap the rewards."